Certain 2-aryl-1,3-cyclohexanediones and their esters are known to be extremely active, biological compounds. U.S. Pat. Nos. 4,175,135 and 4,256,657 and copending application U.S. Ser. No. 781,781 filed Mar. 28, 1977, now U.S. Pat. No. 4,422,870, all of which are herein incorporated by reference, teach the usefulness of these compounds as herbicidal and miticidal agents and as agents for orally controlling acarina ectoparasites on warm-blooded animals.
Cyano-keto-acids, such as the 6-aryl-6-cyano-5-keto-hexanoic acids and/or their esters are important intermediates in the manufacture of the afore-described 2-aryl-1,3-cyclohexanediones.
U.S. Pat. No. 4,256,657 teaches that the coupling of ring-substituted phenylacetonitriles with diesters of alkyl-substituted glutaric acid in a basic medium will result in esters of the cyano-keto-acids described above, e.g. Example XVI of said patent; however, a significant disadvantage to this process is the large molar excess (50 to 200%) of glutaric acid diester required to suppress reaction of a second molecule of ring-substituted phenylacetonitrile with the desired product.